It was a mistake :
But I think I can answer that question about arms on the wheelchair.
NRA will give a permit to a handicapped shooter who needs special consideration. I am in a wheelchair, and sent pictures of myself in each of the 4 standard positions. Prone, Sitting, Kneeling and standing.
For Standing, (well we can't really stand) but the only requirement was that my arms (elbows) could not touch the arms of the chair.
For Sitting, both arms can be supported by the arms of the chair.
For Kneeling, the elbow supporting the forearm of the rifle could be placed on the arm of the chair. The arm of the trigger finger hand must not touch the arm of the chair.
For Prone: Well When I was young I just shot prone like all those guys who can still stand up. Now that I am old, fat and lazy, I have turned to Benchrest. It's sport where we don't have to take or give a handicap.
Prone matches are like that too, but when your get old: Oh the pain, and that goes for those stand-up guys who are over 50 too.